The present invention relates to a method for operating a film leak indicator comprising two films, which are each tensioned inside a frame and which delimit a testing space when a test piece is introduced. In addition, said film leak indicator is equipped with two vacuum pumps. According to the present invention, the testing space is firstly evacuated and the film leak indicator is switched over to a leak search mode after the evacuation is completed and where furthermore during the first evacuation phase of the testing space, only one of the two vacuum pumps and where in the leak search mode only the second vacuum pump is utilized (in accordance with patent application 198 46 799.0). Moreover, the present invention relates to a film leak indicator suited for implementing said method.
In the instance of integral leak detection in accordance with the principal patent application, the test piece is already filled with the test gas, helium in this case, before the measurement. The helium escaping through a present leak is detected in the testing chamber. The natural ambient air already contains a small amount of helium, which, however, is mostly negligible. Owing to filling processes the share of helium may increase in certain cases. Then the detection system of the leak indicator can now no longer discern unambiguously whether the measured helium originates from the test piece or the ambient air trapped in the testing chamber. The measured results become more uncertain; the detection limit of the leak indicator is degraded.
It is the task of the present invention to operate and implement a film leak indicator in accordance with the principal patent application in such a manner that increased helium concentrations in the ambient air will not give rise to incorrect measurements.
This task is solved through the measures contained in the patent claims.
Further advantages and details of the present invention shall be explained with reference to the design examples depicted in the drawing figures.